Coating compositions for use with an overcoated photoresist

ABSTRACT

Organic coating compositions, particularly antireflective coating compositions, are provided that comprise that comprise a component that comprises one or more uracil moieties. Preferred compositions of the invention are useful to reduce reflection of exposing radiation from a substrate back into an overcoated photoresist layer and/or function as a planarizing, conformal or via-fill layer.

This application claims the benefit of priority under 35 U.S.C. § 119(e)to U.S. Provisional Application No. 61/428,896, filed Dec. 31, 2011, theentire contents of which application are incorporated herein byreference.

The present invention relates to uracil compositions that areparticularly useful as a component of a coating composition underlyingan overcoated photoresist.

Photoresists are photosensitive films used for the transfer of images toa substrate. A coating layer of a photoresist is formed on a substrateand the photoresist layer is then exposed through a photomask to asource of activating radiation. The photomask has areas that are opaqueto activating radiation and other areas that are transparent toactivating radiation. Exposure to activating radiation provides aphotoinduced or chemical transformation of the photoresist coating tothereby transfer the pattern of the photomask to the photoresist-coatedsubstrate. Following exposure, the photoresist is developed to provide arelief image that permits selective processing of a substrate.

A major use of photoresists is in semiconductor manufacture where anobject is to convert a highly polished semiconductor slice, such assilicon or gallium arsenide, into a complex matrix of electronconducting paths that perform circuit functions. Proper photoresistprocessing is a key to attaining this object. While there is a stronginterdependency among the various photoresist processing steps, exposureis believed to be one of the most important steps in attaining highresolution photoresist images.

Reflection of activating radiation used to expose a photoresist oftenposes limits on resolution of the image patterned in the photoresistlayer. Reflection of radiation from the substrate/photoresist interfacecan produce spatial variations in the radiation intensity in thephotoresist, resulting in non-uniform photoresist linewidth upondevelopment. Radiation also can scatter from the substrate/photoresistinterface into regions of the photoresist where exposure isnon-intended, again resulting in linewidth variations.

One approach used to reduce the problem of reflected radiation has beenthe use of a radiation absorbing layer interposed between the substratesurface and the photoresist coating layer. See U.S. 2007026458 and2010029556.

Electronic device manufacturers continually seek increased resolution ofa photoresist image patterned over antireflective coating layers.

In one aspect, we provide new uracil-type monomers that are useful toform resins of distinct underlying antireflective coating compositions.

In a further aspect, resins are provided that comprise a reacteduracil-type monomer as disclosed herein.

Preferred resins of the coating compositions of the invention maycomprise one or more polyester linkages. Preferred resins also maycomprise groups in addition to uracil groups such as cyanurate groups.

In a yet further aspect, antireflective compositions are provided thatcomprises a resin as disclosed herein. Preferred additional componentsof an underlying antireflective coating composition include acrosslinking functionality or material. Preferred underlying coatingcompositions are formulated as organic solvent compositions for spin-onapplication to a desired substrate such as a microelectronic wafer.

Preferred underlying coating compositions of the invention arecrosslinked prior to treatment to modulate water contact angle. Suchcrosslinking includes hardening and covalent-bonding forming reactionsbetween one or more composition components.

For antireflective applications, underlying compositions of theinvention also preferably contain a component that comprises chromophoregroups that can absorb undesired radiation used to expose the overcoatedresist layer from reflecting back into the resist layer. Suchchromophore groups may be present with other composition components suchas the resin(s) or an acid generator compound, or the composition maycomprise another component that may comprise such chromophore units,e.g. a small molecule (e.g. MW less than about 1000 or 500) thatcontains one or more chromophore moieties, such as one or moreoptionally substituted phenyl, optionally substituted anthracene oroptionally substituted naphthyl groups.

Generally preferred chromophores for inclusion in coating composition ofthe invention particularly those used for antireflective applicationsinclude both single ring and multiple ring aromatic groups such asoptionally substituted phenyl, optionally substituted naphthyl,optionally substituted anthracenyl, optionally substitutedphenanthracenyl, optionally substituted quinolinyl, and the like.Particularly preferred chromophores may vary with the radiation employedto expose an overcoated resist layer. More specifically, for exposure ofan overcoated resist at 248 nm, optionally substituted anthracene andoptionally substituted naphthyl are preferred chromophores of theantireflective composition. For exposure of an overcoated resist at 193nm, optionally substituted phenyl and optionally substituted naphthylare particularly preferred chromophores of the antireflectivecomposition. Preferably, such chromophore groups are linked (e.g.pendant groups) to a resin component of the antireflective composition.

As discussed above, coating compositions of the invention preferably arecrosslinking compositions and contain a material that will crosslink orotherwise cure upon e.g. thermal or activating radiation treatment.Typically, the composition will contain a crosslinker component, e.g. anamine-containing material such as a melamine, glycouril orbenzoguanamine compound or resin. Preferably, crosslinking compositionsof the invention can be cured through thermal treatment of thecomposition coating layer. Suitably, the coating composition alsocontains an acid or more preferably an acid generator compound,particularly a thermal acid generator compound, to facilitate thecrosslinking reaction.

For use as an antireflective coating composition, as well as otherapplications such as via-fill, preferably the composition is crosslinkedprior to applying a photoresist composition layer over the compositionlayer.

A variety of photoresists may be used in combination (i.e. overcoated)with a coating composition of the invention. Preferred photoresists foruse with the antireflective compositions of the invention arechemically-amplified resists, especially positive-acting photoresiststhat contain one or more photoacid generator compounds and a resincomponent that contains units that undergo a deblocking or cleavagereaction in the presence of photogenerated acid, such asphotoacid-labile ester, acetal, ketal or ether units. Negative-actingphotoresists also can be employed with coating compositions of theinvention, such as resists that crosslink (i.e. cure or harden) uponexposure to activating radiation. Preferred photoresists for use with acoating composition of the invention may be imaged with relativelyshort-wavelength radiation, e.g. radiation having a wavelength of lessthan 300 nm or less than 260 nm such as 248 nm, or radiation having awavelength of less than about 200 nm such as 193 nm EUV and other highenergy imaging also will be suitable.

The invention further provides methods for forming a photoresist reliefimage and novel articles of manufacture comprising substrates (such as amicroelectronic wafer substrate) coated with a coating composition ofthe invention alone or in combination with a photoresist composition.

Other aspects of the invention are disclosed infra.

We now provide new organic coating compositions that are particularlyuseful with an overcoated photoresist layer. Preferred coatingcompositions of the invention may be applied by spin-coating (spin-oncompositions) and formulated as a solvent composition. The coatingcompositions of the invention are especially useful as antireflectivecompositions for an overcoated photoresist and/or as planarizing orvia-fill compositions for an overcoated photoresist composition coatinglayer.

As discussed above, uracil-type compounds are provided. Preferred uracilcomponents include those that comprise groups of the following Formula(I):

wherein R is a hydrogen or non-hydrogen substituent such as halogen (F,Cl, Br, or I, particularly F), nitro, optionally substituted alkyl (e.g.optionally substituted C₁₋₁₀ alkyl), optionally substituted alkenyl oralkynyl preferably having 2 to about 10 carbon atoms such as such asallyl, optionally substituted alkanoyl preferably having 1 to about 10carbon atoms; optionally substituted alkoxy (including epoxy) preferablyhaving 1 to about 10 carbon atoms such as methoxy, propoxy, butoxy;optionally substituted alkylthio preferably having 1 to about 10 carbonatoms; optionally substituted alkylsulfinyl preferably 1 to about 10carbon atoms; optionally substituted alkylsulfonyl preferably having 1to about 10 carbon atoms; optionally substituted carboxy preferably have1 to about 10 carbon atoms (which includes groups such as —COOR′ whereR′ is H or C₁₋₈alkyl, including esters that are substantiallynon-reactive with photoacid); optionally substituted alkaryl such asoptionally substituted benzyl, optionally substituted carbocyclic arylsuch as optionally substituted phenyl, naphthyl, acenaphthyl, oroptionally substituted heteralicyclic or heteroaromatic group such asmethylphthalimide, N-methyl-1,8-phthalimide; and

each R1 is the same or different and may represent a hydrogen, chemicalbond (e.g. where the uracil moiety is linked as a member of a resinchain), or a non-hydrogen substituent such as specified above for R.

In a preferred aspect, uracil-containing monomers are provided thatcomprise halo-substitution, particularly fluoro or chloro substation.Also preferred are resins provided by reaction of such monomercompounds.

Resins of Underlying Coating Compositions:

As discussed above, preferred resins include those that comprise one ormore uracil moieties, including groups of the structure of Formula (I)above. Suitably, the one or more uracil moieties may be pendant to aresin backbone, or alternatively may be resin backbone linkages e.g.linked through each ring nitrogen or a uracil group.

Uracil resins of the invention may be synthesized by a variety ofmethods, e.g. though polymerization of one or more monomers thatcomprise uracil groups such as through an acidic or basic condensationreaction can be suitable. Particularly preferred uracil monomer andresin synthesis are set forth in the examples which follow. Preferably,at least about 1, 2, 3, 4 or 5 percent of the total repeat units of theformed resin comprise one or more uracil moieties, more preferably atleast about 10, 15, 20, 25, 30, 35, 40, 45, 50 or 55 percent of thetotal repeat units of the formed resin.

Particularly preferred uracil resins of the invention comprisespolyester linkages, i.e. polyester resins are preferred in certainaspects if the invention. Polyester resins can be readily prepared byreaction of one or more polyol reagents with one or moreuracil-containing monomers. Suitable polyol reagents include diols,glycerols and triols such as e.g. diols such as diol is ethylene glycol,1,2-propylene glycol, 1,3-propylene glycol, butane diol, pentane diol,cyclobutyl diol, cyclopentyl diol, cyclohexyl diol,dimethylolcyclohexane, and triols such as glycerol, trimethylolethane,trimethylolpropane and the like. Particularly preferred polyol reagentsare set forth in the examples which follow.

Resins of coating compositions of the invention may comprise a varietyof additional groups such as cyanurate groups, as disclosed in U.S. Pat.No. 6,852,421.

Particularly preferred resins of the invention may comprises one or moreuracil groups, one or more cyanurate groups and polyester linkages.

As discussed, for antireflective applications, suitably one or more ofthe compounds reacted to form the resin comprise a moiety that canfunction as a chromophore to absorb radiation employed to expose anovercoated photoresist coating layer. For example, a phthalate compound(e.g. a phthalic acid or dialkyl phthalate (i.e. di-ester such as eachester having 1-6 carbon atoms, preferably a di-methyl or ethylphthalate) may be polymerized with an aromatic or non-aromatic polyoland optionally other reactive compounds to provide a polyesterparticularly useful in an antireflective composition employed with aphotoresist imaged at sub-200 nm wavelengths such as 193 nm Similarly,resins to be used in compositions with an overcoated photoresist imagedat sub-300 nm wavelengths or sub-200 nm wavelengths such as 248 nm or193 nm, a naphthyl compound may be polymerized, such as a naphthylcompound containing one or two or more carboxyl substituents e.g.dialkyl particularly di-C₁₋₆alkyl naphthalenedicarboxylate. Reactiveanthracene compounds also are preferred, e.g. an anthracene compoundhaving one or more carboxy or ester groups, such as one or more methylester or ethyl ester groups.

The compound that contains a chromophore unit also may contain one orpreferably two or more hydroxy groups and be reacted with acarboxyl-containing compound. For example, a phenyl compound oranthracene compound having one, two or more hydroxyl groups may bereacted with a carboxyl-containing compound.

Additionally, underlying coating composition that are employed forantireflective purposes may contain a material that contains chromophoreunits that is separate from a resin component that provides watercontact angle modulation (e.g. a resin that contains photoacid-labilegroups and/or base-reactive groups. For instance, the coatingcomposition may comprise a polymeric or non-polymeric compound thatcontain phenyl, anthracene, naphthyl, etc. units. It is often preferred,however, that the one or more resins that provide water contact anglemodulation also chromophore moieties.

Preferably resins of underlying coating compositions of the invention(including uracil-containing resins) will have a weight averagemolecular weight (Mw) of about 1,000 to about 10,000,000 daltons, moretypically about 2,000 to about 100,000 daltons, and a number averagemolecular weight (Mn) of about 500 to about 1,000,000 daltons. Molecularweights (either Mw or Mn) of the polymers of the invention are suitablydetermined by gel permeation chromatography.

The uracil-containing component (e.g. uracil-containing) resin will bethe major solids component of an underlying coating composition in manypreferred embodiments. As referred to herein, solids of a coatingcomposition refers to all materials of the coating composition exceptsolvent carrier. In certain aspects, the uracil-containing component maybe a minor portion (e.g. less than 50% of total solids) of a coatingcomposition and be suitably blended with one or more other resins thatdo not contain uracil substitution.

As mentioned, preferred underlying coating compositions of the inventioncan be crosslinked, e.g. by thermal and/or radiation treatment. Forexample, preferred underlying coating compositions of the invention maycontain a separate crosslinker component that can crosslink with one ormore other components of the coating composition. Generally preferredcrosslinking coating compositions comprise a separate crosslinkercomponent. Particularly preferred coating compositions of the inventioncontain as separate components: a resin, a crosslinker, and an acidsource such as a thermal acid generator compound. Thermal-inducedcrosslinking of the coating composition by activation of the thermalacid generator is generally preferred.

Suitable thermal acid generator compounds for use in a coatingcomposition include ionic or substantially neutral thermal acidgenerators, e.g. an ammonium arenesulfonate salt, for catalyzing orpromoting crosslinking during curing of an antireflective compositioncoating layer. Typically one or more thermal acid generators are presentin an coating composition in a concentration from about 0.1 to 10percent by weight of the total of the dry components of the composition(all components except solvent carrier), more preferably about 2 percentby weight of the total dry components.

Preferred crosslinking-type coating compositions of the invention alsocontain a crosslinker component. A variety of crosslinkers may beemployed, including those crosslinkers disclosed in Shipley EuropeanApplication 542008 incorporated herein by reference. For example,suitable coating composition crosslinkers include amine-basedcrosslinkers such as melamine materials, including melamine resins suchas manufactured by Cytec Industries and sold under the tradename ofCymel 300, 301, 303, 350, 370, 380, 1116 and 1130. Glycolurils areparticularly preferred including glycolurils available from CytecIndustries. Benzoquanamines and urea-based materials also will besuitable including resins such as the benzoquanamine resins availablefrom Cytec Industries under the name Cymel 1123 and 1125, and urearesins available from Cytec Industries under the names of Powderlink1174 and 1196. In addition to being commercially available, suchamine-based resins may be prepared e.g. by the reaction of acrylamide ormethacrylamide copolymers with formaldehyde in an alcohol-containingsolution, or alternatively by the copolymerization of N-alkoxymethylacrylamide or methacrylamide with other suitable monomers.

A crosslinker component of a coating composition of the invention ingeneral is present in an amount of between about 5 and 50 weight percentof total solids (all components except solvent carrier) of theantireflective composition, more typically in an amount of about 7 to 25weight percent total solids.

Coating compositions of the invention, particularly for reflectioncontrol applications, also may contain additional dye compounds thatabsorb radiation used to expose an overcoated photoresist layer. Otheroptional additives include surface leveling agents, for example, theleveling agent available under the tradename Silwet 7604, or thesurfactant FC 171 or FC 431 available from the 3M Company.

Underlying coating compositions of the invention also may contain othermaterials such as a photoacid generator, including a photoacid generatoras discussed for use with an overcoated photoresist composition. SeeU.S. Pat. No. 6,261,743 for a discussion of such use of a photoacidgenerator in an antireflective composition.

To make a liquid coating composition of the invention, the components ofthe coating composition are dissolved in a suitable solvent such as, forexample, one or more oxyisobutyric acid esters particularlymethyl-2-hydroxyisobutyrate as discussed above, ethyl lactate or one ormore of the glycol ethers such as 2-methoxyethyl ether (diglyme),ethylene glycol monomethyl ether, and propylene glycol monomethyl ether;solvents that have both ether and hydroxy moieties such as methoxybutanol, ethoxy butanol, methoxy propanol, and ethoxy propanol; methyl2-hydroxyisobutyrate; esters such as methyl cellosolve acetate, ethylcellosolve acetate, propylene glycol monomethyl ether acetate,dipropylene glycol monomethyl ether acetate and other solvents such asdibasic esters, propylene carbonate and gamma-butyro lactone. Theconcentration of the dry components in the solvent will depend onseveral factors such as the method of application. In general, thesolids content of an underlying coating composition varies from about0.5 to 20 weight percent of the total weight of the coating composition,preferably the solids content varies from about 0.5 to 10 weight of thecoating composition.

Exemplary Photoresist Systems

A variety of photoresist compositions can be employed with coatingcompositions of the invention, including positive-acting andnegative-acting photoacid-generating compositions. Photoresists usedwith antireflective compositions of the invention typically comprise aresin binder and a photoactive component, typically a photoacidgenerator compound. Preferably the photoresist resin binder hasfunctional groups that impart alkaline aqueous developability to theimaged resist composition.

As discussed above, particularly preferred photoresists for use withunderlying coating compositions of the invention arechemically-amplified resists, particularly positive-actingchemically-amplified resist compositions, where the photoactivated acidin the resist layer induces a deprotection-type reaction of one or morecomposition components to thereby provide solubility differentialsbetween exposed and unexposed regions of the resist coating layer. Anumber of chemically-amplified resist compositions have been described,e.g., in U.S. Pat. Nos. 4,968,581; 4,883,740; 4,810,613; 4,491,628 and5,492,793. Coating compositions of the invention are particularlysuitably used with positive chemically-amplified photoresists that haveacetal groups that undergo deblocking in the presence of a photoacid.Such acetal-based resists have been described in e.g. U.S. Pat. Nos.5,929,176 and 6,090,526.

Underlying coating compositions of the invention also may be used withother positive resists, including those that contain resin binders thatcomprise polar functional groups such as hydroxyl or carboxylate and theresin binder is used in a resist composition in an amount sufficient torender the resist developable with an aqueous alkaline solution.Generally preferred resist resin binders are phenolic resins includingphenol aldehyde condensates known in the art as novolak resins, homo andcopolymers or alkenyl phenols and homo and copolymers ofN-hydroxyphenyl-maleimides.

Preferred positive-acting photoresists for use with an underlyingcoating composition of the invention contains an imaging-effectiveamount of photoacid generator compounds and one or more resins that areselected from the group of:

1) a phenolic resin that contains acid-labile groups that can provide achemically amplified positive resist particularly suitable for imagingat 248 nm Particularly preferred resins of this class include: i)polymers that contain polymerized units of a vinyl phenol and an alkylacrylate, where the polymerized alkyl acrylate units can undergo adeblocking reaction in the presence of photoacid. Exemplary alkylacrylates that can undergo a photoacid-induced deblocking reactioninclude e.g. t-butyl acrylate, t-butyl methacrylate, methyladamantylacrylate, methyl adamantyl methacrylate, and other non-cyclic alkyl andalicyclic acrylates that can undergo a photoacid-induced reaction, suchas polymers in U.S. Pat. Nos. 6,042,997 and 5,492,793; ii) polymers thatcontain polymerized units of a vinyl phenol, an optionally substitutedvinyl phenyl (e.g. styrene) that does not contain a hydroxy or carboxyring substituent, and an alkyl acrylate such as those deblocking groupsdescribed with polymers i) above, such as polymers described in U.S.Pat. No. 6,042,997; and iii) polymers that contain repeat units thatcomprise an acetal or ketal moiety that will react with photoacid, andoptionally aromatic repeat units such as phenyl or phenolic groups; suchpolymers have been described in U.S. Pat. Nos. 5,929,176 and 6,090,526.

2) a resin that is substantially or completely free of phenyl or otheraromatic groups that can provide a chemically amplified positive resistparticularly suitable for imaging at sub-200 nm wavelengths such as 193nm Particularly preferred resins of this class include: i) polymers thatcontain polymerized units of a non-aromatic cyclic olefin (endocyclicdouble bond) such as an optionally substituted norbornene, such aspolymers described in U.S. Pat. Nos. 5,843,624, and 6,048,664; ii)polymers that contain alkyl acrylate units such as e.g. t-butylacrylate, t-butyl methacrylate, methyladamantyl acrylate, methyladamantyl methacrylate, and other non-cyclic alkyl and alicyclicacrylates; such polymers have been described in U.S. Pat. No. 6,057,083;European Published Applications EP01008913A1 and EP00930542A1; and U.S.pending patent application Ser. No. 09/143,462; iii) polymers thatcontain polymerized anhydride units, particularly polymerized maleicanhydride and/or itaconic anhydride units, such as disclosed in EuropeanPublished Application EP01008913A1 and U.S. Pat. No. 6,048,662.

3) a resin that contains repeat units that contain a hetero atom,particularly oxygen and/or sulfur (but other than an anhydride, i.e. theunit does not contain a keto ring atom), and preferable aresubstantially or completely free of any aromatic units. Preferably, theheteroalicyclic unit is fused to the resin backbone, and furtherpreferred is where the resin comprises a fused carbon alicyclic unitsuch as provided by polymerization of a norborene group and/or ananhydride unit such as provided by polymerization of a maleic anhydrideor itaconic anhydride. Such resins are disclosed in PCT/US01/14914 andU.S. application Ser. No. 09/567,634.

4) a resin that contains fluorine substitution (fluoropolymer), e.g. asmay be provided by polymerization of tetrafluoroethylene, a fluorinatedaromatic group such as fluoro-styrene compound, and the like. Examplesof such resins are disclosed e.g. in PCT/US99/21912.

Suitable photoacid generators to employ in a positive or negative actingphotoresist overcoated over a coating composition of the inventioninclude imidosulfonates such as compounds of the following formula:

wherein R is camphor, adamantane, alkyl (e.g. C₁₋₁₂ alkyl) andfluoroalkyl such as fluoro (C₁₋₁₈alkyl) e.g. RCF₂— where R is optionallysubstituted adamantyl.

Also preferred is a triphenyl sulfonium PAG, complexed with anions suchas the sulfonate anions mentioned above, particularly a perfluoroalkylsulfonate such as perfluorobutane sulfonate.

Other known PAGS also may be employed in the resists of the invention.Particularly for 193 nm imaging, generally preferred are PAGS that donot contain aromatic groups, such as the above-mentionedimidosulfonates, in order to provide enhanced transparency.

Other suitable photoacid generators for use in compositions of theinvention include for example: onium salts, for example,triphenylsulfonium trifluoromethanesulfonate,(p-tert-butoxyphenyl)diphenylsulfonium trifluoromethanesulfonate,tris(p-tert-butoxyphenyl)sulfonium trifluoromethanesulfonate,triphenylsulfonium p-toluenesulfonate, nitrobenzyl derivatives, forexample, 2-nitrobenzyl p-toluenesulfonate, 2,6-dinitrobenzylp-toluenesulfonate, and 2,4-dinitrobenzyl p-toluenesulfonate; sulfonicacid esters, for example, 1,2,3-tris(methanesulfonyloxy)benzene,1,2,3-tris(trifluoromethanesulfonyloxy)benzene, and1,2,3-tris(p-toluenesulfonyloxy)benzene; diazomethane derivatives, forexample, bis(benzenesulfonyl)diazomethane,bis(p-toluenesulfonyl)diazomethane; glyoxime derivatives, for example,bis-O-(p-toluenensulfonyl)-α-dimethylglyoxime, andbis-O-(n-butanesulfonyl)-α-dimethylglyoxime; sulfonic acid esterderivatives of an N-hydroxyimide compound, for example,N-hydroxysuccinimide methanesulfonic acid ester, N-hydroxysuccinimidetrifluoromethanesulfonic acid ester; and halogen-containing triazinecompounds, for example,2-(4-methoxyphenyl)-4,6-bis(trichloromethyl)-1,3,5-triazine, and2-(4-methoxynaphthyl)-4,6-bis(trichloromethyl)-1,3,5-triazine. One ormore of such PAGs can be used.

A preferred optional additive of resists of the invention is an addedbase, particularly tetrabutylammonium hydroxide (TBAH), ortetrabutylammonium lactate, which can enhance resolution of a developedresist relief image. For resists imaged at 193 nm, a preferred addedbase is a lactate salt of tetrabutylammonium hydroxide as well asvarious other amines such as triisopropanol, diazabicyclo undecene ordiazabicyclononene. The added base is suitably used in relatively smallamounts, e.g. about 0.03 to 5 percent by weight relative to the totalsolids.

Preferred negative-acting resist compositions for use with an overcoatedcoating composition of the invention comprise a mixture of materialsthat will cure, crosslink or harden upon exposure to acid, and aphotoacid generator.

Particularly preferred negative-acting resist compositions comprise aresin binder such as a phenolic resin, a crosslinker component and aphotoactive component of the invention. Such compositions and the usethereof have been disclosed in European Patent Applications 0164248 and0232972 and in U.S. Pat. No. 5,128,232 to Thackeray et al. Preferredphenolic resins for use as the resin binder component include novolaksand poly(vinylphenol)s such as those discussed above. Preferredcrosslinkers include amine-based materials, including melamine,glycolurils, benzoguanamine-based materials and urea-based materials.Melamine-formaldehyde resins are generally most preferred. Suchcrosslinkers are commercially available, e.g. the melamine resins soldby Cytec Industries under the trade names Cymel 300, 301 and 303.Glycoluril resins are sold by Cytec Industries under trade names Cymel1170, 1171, 1172, Powderlink 1174, and benzoguanamine resins are soldunder the trade names of Cymel 1123 and 1125.

Photoresists of the invention also may contain other optional materials.For example, other optional additives include anti-striation agents,plasticizers, speed enhancers, dissolution inhibitors, etc. Suchoptional additives typically will be present in minor concentrations ina photoresist composition except for fillers and dyes which may bepresent in relatively large concentrations, e.g., in amounts of fromabout 5 to 30 percent by weight of the total weight of a resist's drycomponents.

Lithographic Processing

In use, a coating composition of the invention is applied as a coatinglayer to a substrate by any of a variety of methods such as spincoating. The coating composition in general is applied on a substratewith a dried layer thickness of between about 0.02 and 0.5 μm,preferably a dried layer thickness of between about 0.04 and 0.20 μm.The substrate is suitably any substrate used in processes involvingphotoresists. For example, the substrate can be silicon, silicon dioxideor aluminum-aluminum oxide microelectronic wafers. Gallium arsenide,silicon carbide, ceramic, quartz or copper substrates may also beemployed. Substrates for liquid crystal display or other flat paneldisplay applications are also suitably employed, for example glasssubstrates, indium tin oxide coated substrates and the like. Substratesfor optical and optical-electronic devices (e.g. waveguides) also can beemployed.

Preferably the applied coating layer is cured before a photoresistcomposition is applied over the underlying coating composition. Cureconditions will vary with the components of the underlying coatingcomposition. Particularly the cure temperature will depend on thespecific acid or acid (thermal) generator that is employed in thecoating composition. Typical cure conditions are from about 80° C. to225° C. for about 0.5 to 5 minutes. Cure conditions preferably renderthe coating composition coating layer substantially insoluble to thephotoresist solvent as well as an alkaline aqueous developer solution.

After such curing, a photoresist is applied above the surface of theapplied coating composition. As with application of the bottom coatingcomposition layer(s), the overcoated photoresist can be applied by anystandard means such as by spinning, dipping, meniscus or roller coating.Following application, the photoresist coating layer is typically driedby heating to remove solvent preferably until the resist layer is tackfree. Optimally, essentially no intermixing of the bottom compositionlayer and overcoated photoresist layer should occur.

The resist layer is then imaged with activating radiation through a maskin a conventional manner The exposure energy is sufficient toeffectively activate the photoactive component of the resist system toproduce a patterned image in the resist coating layer. Typically, theexposure energy ranges from about 3 to 300 mJ/cm² and depending in partupon the exposure tool and the particular resist and resist processingthat is employed. The exposed resist layer may be subjected to apost-exposure bake if desired to create or enhance solubilitydifferences between exposed and unexposed regions of a coating layer.For example, negative acid-hardening photoresists typically requirepost-exposure heating to induce the acid-promoted crosslinking reaction,and many chemically amplified positive-acting resists requirepost-exposure heating to induce an acid-promoted deprotection reaction.Typically post-exposure bake conditions include temperatures of about50° C. or greater, more specifically a temperature in the range of fromabout 50° C. to about 160° C.

The photoresist layer also may be exposed in an immersion lithographysystem, i.e. where the space between the exposure tool (particularly theprojection lens) and the photoresist coated substrate is occupied by animmersion fluid, such as water or water mixed with one or more additivessuch as cesium sulfate which can provide a fluid of enhanced refractiveindex. Preferably the immersion fluid (e.g., water) has been treated toavoid bubbles, e.g. water can be degassed to avoid nanobubbles.

References herein to “immersion exposing” or other similar termindicates that exposure is conducted with such a fluid layer (e.g. wateror water with additives) interposed between an exposure tool and thecoated photoresist composition layer.

The exposed resist coating layer is then developed, preferably with anaqueous based developer such as an alkali exemplified by tetra butylammonium hydroxide, sodium hydroxide, potassium hydroxide, sodiumcarbonate, sodium bicarbonate, sodium silicate, sodium metasilicate,aqueous ammonia or the like. Alternatively, organic developers can beused. In general, development is in accordance with art recognizedprocedures. Following development, a final bake of an acid-hardeningphotoresist is often employed at temperatures of from about 100° C. toabout 150° C. for several minutes to further cure the developed exposedcoating layer areas.

The developed substrate may then be selectively processed on thosesubstrate areas bared of photoresist, for example, chemically etching orplating substrate areas bared of photoresist in accordance withprocedures well known in the art. Suitable etchants include ahydrofluoric acid etching solution and a plasma gas etch such as anoxygen plasma etch. A plasma gas etch removes the underlying coatinglayer.

A plasma etch conducted by the following protocol: a coated substrate(e.g., substrate coated with an underlying coating composition andresist in accordance with the invention) is placed in a plasma etchchamber (e.g., Mark II Oxide Etch Chamber) at 25 mT pressure, top powerof 600 watts, 33 CHF) (Sccm), 7 O₂ (Sccm) and 80 Ar (Sccm).

The following non-limiting examples are illustrative of the invention.All documents mentioned herein are incorporated herein by reference.

EXAMPLE 1 Uracil Monomer Synthesis: Synthesis of 1,3 bis(t-butylacetate)-5-Nitrouracil

The title compound was synthesized as depicted in the above Scheme asfollows. In a 500 mL three necked oven dried round bottom flask equippedwith a magnetic stirrer, 25 g (0.159 mol) of 5-NitroUracil and 53.9 g(0.39 mol) of Potassium Carbonate (K₂CO₃) were suspended in 100 mL ofDimethylformadide (DMF) and the mixture stirred at room temperature for1 hour, resulting in a thick gel. 77.3 g (0.39 mol) of t-Butylbromoacetate dissolved in 50 mL of DMF was slowly added to the reactionmixture using a dropping funnel over a period of one hour and thereaction stirred for another 12 hr until completion was ascertained byTLC analysis (3:97 Methanol/Chloroform). The reaction was quenched bypouring the mixture slowly into 400 mL of 0.1% HCl solution, extractedinto 300 mL of Ethyl Acetate, washed with water and brine to a neutralpH. The Ethyl acetate extracts were then dried over Sodium Sulphate,filtered and concentrated in the rotary evaporator affording 55 g or ayellowish oil. The oil was purified further by passing it through asilica gel plug eluting the desired product with chloroform. The solventwas evaporated to dryness and the clear oil recrystallized out ofacetone and cold water affording 50 g of the pure product as a whitesolid in a 90% yield. ¹H NMR 400 MHz (CDCl₃) δ 8.8 (s, 1H), 4.61 (s, 2H,CH₂), 4.58 (s, 2H, CH₂), 1.49 (s, 9H, CH₃), 1.46 (s, 9H, CH₃). ¹³C NMR400 MHz (CDCl₃) δ 165.6, 165.2, 153.7, 149.2, 149.8, 84.4, 83.0, 51.4,43.4, 27.93, 27.92.

EXAMPLE 2 Uracil Monomer Synthesis: Synthesis of 1,3 bis(t-butylacetate)-5-Fluorouracil

The title compound was synthesized as depicted in the above Scheme asfollows. To a suspension of 5-Fluorouracil (40 g, 0.31 mol) in DMF (300mL), was added t-Butyl bromoacetate (131.66 mL, 0.67 mol) anddiisopropylethylamine (87.3 mL, 0.13 mol) at room temperature, theresultant mixture placed in a silicon oil bath and refluxed at 80° C.for 12 hours. Initially, the reaction mixture formed a suspension, butas the reaction progressed all the reactants went into solution. Uponcompletion ascertained by TLC analysis (Methanol/Chloroform ˜3/97), thereaction was preconcentrated to smaller volume and later quenched bypouring into dilute acid (0.1% HCl, 400 mL) and extracted into ethylacetate (350 mL), washed once with distilled water (400 mL) and driedover sodium sulfate and solvent evaporated under vacuum affording inquantitative yields a yellowish oil product. This oil was purifiedfurther by passing through a silica plug eluting with chloroform, Rotaevaporated to dryness and recrystallized out of ethyl acetate andhexanes, affording 100 g of white crystals in 91% yields. ¹H NMR 400 MHz(CDCl₃) δ 7.4 (s, 1H), 6.74 (d, J=4.4 Hz, 1H), 4.67 (s, 2H, CH₂), 4.23(s, 2H, CH₂), 1.46 (s, 18H, CH₃). ¹³C NMR 400 MHz (CDCl₃) δ 166.9,166.7, 152.7, 152.4, 149.8, 139.4, 137.6, 120.4, 120.1, 82.3, 81.7,50.0, 43.8, 28.2

EXAMPLE 3 Uracil Polymer Synthesis

The polyester uracil polymer as depicted in the above Scheme wasprepared as follows. 1,3 bis(t-butyl acetate)-5-Fluorouracil,1,3,5-Tris(2-Hydroxyethyl)cyanuric acid, p-toluenesulfonic acid andanisole (50% solids) were charged into a 100 mL three necked oven driedround bottom flask equipped with a overhead stirrer, dean stark trap,heating mantle, temperature control box, temperature probe andcondenser. The reactants were heated at 140° C. until the theoreticalamount of distillate required was collected. The resultant polymer wasallowed to cool and diluted to 25% solids using tetrahydrofuran andprecipitated out of methyl tertbutyl ether/isopropanol (80/20) mixture.The obtained product was filtered and washed with copious amounts ofprecipitating solvent and afforded the desired polymer in 50% yields.Molecular weight was obtained using Gel permeation chromatography withpolystyrene standards.

EXAMPLE 4 Uracil Polymer Synthesis

By procedures corresponding to those of Example 3 above, the abovedepicted polymers containing uracil moieties and polyester linkages canbe prepared. R can be suitably a variety of hydrogen and non-hydrogensubstituents as specified above for Formula I including e.g. halogensuch as fluoro, bromo or chloro, optionally substituted C1-10alkyl,optionally substituted C1-10alkoxy and nitro.

EXAMPLE 5 Di and Tri-Functional Alcohols

The above depicted polyols are useful for polymer (including polyester)syntheses.

EXAMPLE 6 Antireflective Composition Preparation

An anti-reflective casting solution comprising of 3.237 g of polymerfrom Example 3, 5.768 g of tetramethoxymethyl glycoluril, 0.371 gsolution of ammoniated para-toluene sulfonic acid and 490.624 g ofmethyl-2-hydroxyisobutyrate are admixed and filtered through a 0.2μTeflon filter.

EXAMPLE 7 Lithographic Processing

This formulated uracil resin-containing coating composition is spincoated onto a silicon microchip wafer and is cured at 210° C. for 60seconds on a vacuum hotplate to provide a hardened coating layer.

A commercially available 193 nm positive-acting photoresist is thenspin-coated over the cured coating composition layer. The applied resistlayer is soft-baked at 100° C. for 60 seconds on a vacuum hotplate,exposed to patterned 193 nm radiation through a photomask, post-exposurebaked at 110° C. for 60 seconds and then developed with 0.26 N aqueousalkaline developer where both the photoresist later and underlyingcoating composition are removed in areas defined by the photomask.

What is claimed is:
 1. A coated substrate comprising: (a) a layer of acoating composition on a substrate, the coating composition comprising apolyester resin that comprises one or more uracil moieties, wherein thecomposition coating layer further comprises phenyl or anthacene groups,or where the uracil moieties are halogen-substituted; and (b) aphotoresist layer over the coating composition layer.
 2. The substrateof claim 1 wherein the resin further comprises one or more cyanurategroups.
 3. The substrate of claim 1 wherein the coating compositionfurther comprises phenyl or anthracene groups.
 4. A method of forming aphotoresist relief image, comprising: (a) applying a coating compositionon a substrate, the coating composition comprising a polyester resinthat comprises one or more uracil moieties, wherein the coatingcomposition further comprises phenyl or anthacene groups, or where theuracil moieties are halogen-substituted; (b) applying a photoresistcomposition above the coating composition layer; and (c) exposing anddeveloping the photoresist layer to provide a resist relief image. 5.The method of claim 4 wherein the coating composition further comprisesa component that comprises phenyl or anthracene groups.
 6. The method ofclaim 4 wherein the photoresist is exposed with 193 nm radiation.
 7. Themethod of claim 4 wherein the applied coating composition is crosslinkedprior to applying the photoresist composition.
 8. An antireflectivecomposition for use with an overcoated photoresist composition, theantireflective composition comprising a polyester resin that comprisesone or more uracil moieties, wherein the antireflective compositionfurther comprises phenyl or anthacene groups, or where the uracilmoieties are halogen-substituted.
 9. The antireflective composition ofclaim 8 wherein the resin comprises phenyl groups.
 10. Theantireflective composition of claim 8 wherein the composition furthercomprises a crosslinker component.
 11. The substrate of claim 1 whereinthe uracil moieties correspond to the following Formula (I):

wherein R is a hydrogen or non-hydrogen substituent; and each R1 is thesame or different any may be hydrogen, a chemical bond or a non-hydrogensubstituent.
 12. The method of claim 4 wherein the uracil moietiescorrespond to the following Formula (I):

wherein R is a hydrogen or non-hydrogen substituent; and each R1 is thesame or different any may be hydrogen, a chemical bond or a non-hydrogensubstituent.
 13. The composition of claim 8 wherein the uracil linkagescorrespond to the following Formula (I):

wherein R is a hydrogen or non-hydrogen substituent; and each R1 is thesame or different any may be hydrogen, a chemical bond or a non-hydrogensubstituent.
 14. The substrate of claim 1 wherein the uracil moietiesare fluoro-substituted.
 15. The method of claim 4 wherein the uracilmoieties are fluoro-substituted.
 16. The composition of claim 8 whereinthe uracil moieties are fluoro-substituted.
 17. The substrate of claim11 wherein R is fluoro or nitro.
 18. The method of claim 12 wherein R isfluoro or nitro.
 19. The composition of claim 13 wherein R is fluoro ornitro.
 20. The substrate of claim 1 wherein the uracil moieties arehalogen-substituted.
 21. The method of claim 4 wherein the uracilmoieties are halogen-substituted.
 22. The composition of claim 8 whereinthe uracil moieties are halogen-substituted.